Pay membership fees even though you don't know about it?

Good evening, This is what happened to me: I received an invoice today from a sports club. It states that I am in arrears with the so-called membership fee for this sports club. This arrears amounts to €24.00. I can say that I've never heard of this community in my life, know nothing about this…

Which club could I go to in order to make contacts (note text)?

I'm currently experiencing increasingly severe and frequent problems with both knees. My right knee has osteoarthritis, and my left knee probably has a partial re-rupture of the anterior cruciate ligament and grade 3 cartilage damage. If I run anything faster than my own walking pace—and yes, I'm a real slow walker—my knees immediately start protesting…